Easy-start reversing mechanism for machine-tool tables



Dec. 19, 1922. M

w. F. FRASER. EASY START REVERSING MECHANISM FOR MACHINE TO0L-TABLES.

INVOR FILED MAY 5,1922.

Ba it knownithat L citizen of the United Si-ates 0f Amar eathers in the Cgmq siding at W ter and faiuie 0f vent d cefiain new uni meats; 3w. EaS' ve' Eh, lqwing all tiQn 5 particalarly is a 1 i; or mingmi easy 1;. in directicn gfiiasigeneu 22 79 i; mount-Ki 0n b i cm msie m. ii L;

W Maui 115.

tion to provide screw and nut for recipim I i by Ir iooi table at a mpiii w i ,y an we a m (the monian of lfi'YGi'HP. on Tim i and other s apparent from '1" siga'ii is my ii'uention iesi in em'ni z mitl'an of partsysen forth in iih s Pam mix-va ved by the claims almuruicai in the drawings in which um cn'ihoiiiinaznt or' my invention iiidSiililiidZ Figure 1 is i l'tlgii'iknilili'ff Qii'Y 573' in section, showing my i'ev. me hanism;

Fig. 2 is 11 side elevation. pm-ifi i away anti partly in soctinm propose '50 means for shifting; the cin'tcu i'eiafiiv-e in Fig. 3 is; a su-tiun on the riilii'? 3-3 of nez $10 gradually an i 4 's 2!! Hawaiian of the (21113 xhown iii this and I so 104i from the other" aris; and that ii; may t1 a. detail showing in e iwiaiion the with the motiun operation of the clutch throwing mechanism, rate Wi1ii-h ini 'i 3 sewea i0 1 3 chine in were, the forward lead. of the screw and pie veni; it moving the table. Thie inovemeot of the out rele e ie the treble is @Uhen gradually retarded iii-such manner us to provide increasing 'ahruet upon i he stable which causes the table to more oi: inereesing rate until it reachesoite normal full. epeecl.

To this end i mount rile nui, 30 for rotetion as well as longiturlinul mo'veniieiit within hearings in illie projection depending; from the HE EL' side of he emu. Keyeo on the ends of the nut are we ceui meiniiers and which, as shown in elevation in Fig. i, have surfaces 34-. one. suituhlo shape. These preferably conform to the shape of a grmit y curve, as modified by like (:l1:i.1'&0l%f15$15 of the particular inewltiich they are mounfied. Bearing cam surfaces are rollers 34' and 38 mounted on 39 fixed on the depending nioinhei fl, iheso parts being wronged fl? end oi .u's

r v I "one: i she. lower end of its path, and vice I T cause on autoumtio rev he verse cluicli.

(The fingers 418 and pivotell g mounted on the inside the xdepted to engage jijoieo'tion 5(r0Z1l3l1-2 member 43. The fiver en le of the lingers e5" eml 49 are pro viilei with etuils having spring 52 interposed iherebetween. The lower ends of the fingers 4.8 and 19 are milepteil to alternately engage opposite sides oi the projection 50 as the yoke member l3 moves; to shift the clutch 22. I provide the yoke member with two plungers 53 held by sprin which adopted to he acted upon by pivotully mounted lever The level is provide] with fixed pin 56 exte (iii either side oi the lever and. adept-ed engage the upper ends of line fingers rim-T GOO .zu'ul ell). As shown in 5, if the lever 55 swings to the, right, the right hand spring: presseo plunger Will be uoieo; upon and compress the spring. This action will (3011 U tinue until the pin 56 on the lever 55% facts with. upper end of the finger 49 encl. inovcsthe some so thao ifihe lower encl will h raise and. unlock the projection As soon 2171-; the finger 453 has been unlockei, the tension 0 the right hand spring will z'epiilly throw the yoke i t he rightand consequently Che clutch into the reverse posiiion. soon the lce e3 hue moved the required distance th.v spring acts encl tiuows the 1 111 81 48 into alocked position against the projeciion 50 and thus holds the clutch in the reverse position.

'io effect the operation of the load. and fire mechanism, 1 me Y provide any suitable connections whereby the movement of the table 11 may be uiilized. As illustrated, the lever 5:; is pivoted to the inside of the base on the rotatable stud 57. To the outerenol of: the stud 57 if, fixed a yoke lever 58 so that the levers and 58 are substantial. as a single level. T he yoke of the lever 58 is adapted to be moved. by the rod 60, which is sliilubly mounted in Suitable beau-lugs 62 on the base, only one of which is shown in Fig. by being interposed between the two fixed collars (ii-l and 64 on the rod. The rod is provided with the adjustable clogs 65 and (36 which are positioned so as to be acted upon by a fixed stop 67 depending from the tahle.

l n explanation of the operation of my driving and rexereingr mecha-znisin, assume that it is desire! to start the table towards the left by rotating shaft 28 in the direction of the arrow as shown in Fig. 1. The cam roller 37 is iniiielly at the top of the path 554, and the roller 38 at the bottom of the oath 35, shown in Fig. 4-, so that when ihe shui't. first starts to rotate, the thrust (lueio tim inertia oi the stationary table will result in. the uni; 30 being rotated by the screw. The can: roller 3'? will permit the nut to travel relative to the table at a. variable rate depending always upon the shape of the cam path 34. The firsi part of the cam path is so shaped that the nutstzu-ts rotating with the screw without imparting thrust to die table, but as the roller 3? moves along the cum at a slower longitudinal rate. on increasing thrust, ,is imparted thereto and the tuhle is forced to start into motion. This motion increases until by the time the roller has gone the length of the cum and struck the abutment at the end of the path ehe table is traveling lull speed. No further relative motion be tween table and nut being thereuite poimiiled, the table is driven normull until he clutch is thrown. mien the teole has been lwougl'lt to rest, it is started gradually in the opposite direction by the other cam and cum roller coming into action. The lost motion between the lugs on shaft 28 and gear 2% permits the table to stop gradually under its own nioinenfium.

Having thus described my invention what i claim-as new and (lesire to secure by Letters Fuient is:

1. In a machine tool having c. reciprocatin; table, 21-. driving and reversing mechanieu'i tl'ierelfl'ir comprising 2L driving screw, a nut on the screw movebiy coimcted with said talileynimins i'o rotate said screw in op osite directions. and connections between said nut fly into motion from rest and thereafter drive it at'jts normal speed until reversal in di- "titlon of the screw. 4

f 2- In a machine tool having a reciprocating table, means to reciprocate the same comprising a driving screw, means to rotate "the same in opposite directions, a nut on said screw, and connections comprising co- 3 operating cam members between said nut -10.

and table effective to startthe table gradually into motion when the screw is first rotated and thereafter drive it at a normal rate.

3. In a machine tool having a reciprocable table, a driving and reversing mechanism said parts being so constructed and arranged that the end thrust to move said table is transmitted only through the cam and cam follower and said cam being shaped relative to the screw so as to cause the table start gradually. in motion as the cam fol-,

lower moves along the surface of the cam. 4:. In a machine tool having a reciprocable table, a driving and reversing mechanism therefor comprising a nut rotatabl and longitudinally movable relative to sai table,

a driving screw cooperating with said nut,

and arranged to cause the nut to move relative to said table at a gradually retarded rate while the screw is rotating at uniform velocity until the nut and'table are traveling uniformly together.

5. In a machine tool having a reciprocable table, a nut mounted on the table for rotation and axial movement relative thereto, cams'on the opposite ends of said nut and cam followers on the table. engaging said cams to move the tabldwhen the nut is moved axially, a driving screw c001 )erating with said nut and means to rotate the screw in opposite directions for variable periods of time, said cam parts being so constructed and arranged relative to the nut that initial rotation of the screw causes the nut to rotate and move axially relative to the table at a gradually retarded rate and thereby start the table gradually into motion.

Signed at \Vestboro, Massachusetts, this 3d day of' May, 1922.

WARREN F. FRASER. 

